Customize Post Title Link hover

Hello,

I want to customize the Post title link hover.

I implemented by testing the following code variations both in my CSS file & in Custome CSS plugin area with unfortunately NO result:

.related-post .post-list .item .post_title a: hover {
         color: #1a1a1a;
}

.title .post_title a: hover {
         color: #1a1a1a;
}

.post_title a: hover {
         color: #1a1a1a;
}

Please, How to customize a link hover on Post Title?

On the other hand, I want also to ask if the CSS & settings we made directly in the plugin interface are NOT overridden by updates?

Thank You very much.